The concurrent validity of a portable force plate system for measuring isometric mid-thigh pull

Area of Science:

• Biomechanics
• Sports Science
• Human Movement Analysis

Background:

• Portable force plates offer convenience for isometric mid-thigh pull (IMTP) testing.
• Validation of these portable systems against ground-based systems is crucial for practical application.

Purpose of the Study:

• To examine the concurrent validity of portable force plate systems (FPSs) for IMTP measurements.
• To compare measurements from portable FPSs (ForceIntellec, ForceDecks) with a ground-based FPS (Kistler).

Main Methods:

• Simultaneous collection of vertical ground reaction force (vGRF) during IMTP using two portable and one ground-based FPS.
• Analysis of vGRF data using proprietary software for each FPS.
• Comparison of peak force (PF), net PF, rate of force development (RFD), and force impulses (FIs).

Main Results:

• Good consistency observed between portable and ground-based FPSs, with differences below 5%.
• Minor proportional bias noted in peak force (PF), net PF, and some rate of force development (RFD) intervals.
• No systematic or proportional bias found between portable FPSs for PF, net PF, and FIs, but inconsistencies in RFDs were present.

Conclusions:

• Portable FPSs are valid tools for IMTP measurement.
• Prioritize the use of force impulses (FIs) over rate of force development (RFD) when using different FPSs due to observed inconsistencies.
• Findings support the validation of FPSs, enhancing their research and practical utility.